Many patients, particularly those at risk for health disparities, receive care that is not consistent with the best evidence. Numerous studies have suggested the utility of informatics-based tools at the point of care to facilitate evidence-based practice; however, such tools have not been widely deployed and rigorously evaluated. Furthermore, most studies have focused on physicians rather than on other types of primary care providers such as advanced practice nurses (APNs). Clinical practice guidelines (CPG) are a significant source of evidence, but studies indicate that frequently clinicians either do not adhere to CPG recommendations or fail to document CPG-based care. Informatics tools that integrate CPGs into point of care documentation have demonstrated improved adherence to recommendations, but for the most part these tools have been integrated into desktop rather than mobile systems. The overall goal of this project is to determine if mobile decision support improves adherence to selected CPG recommendations. The specific aims of this study are to: (1) Extend an existing personal digital assistant-based (PDA) APN student clinical log (CL-APN) to include mobile decision support (MODS-APN]) for three CPGs of relevance across APN specialties; (2) Develop a web-based CPG resource site for three CPGs; (3) Using a randomized controlled trial (RCT) design, examine the effect of MODS-APN as compared to CL-APN on: a) percentage of patient encounters in which screening is documented among all eligible encounters; b) percentage of CPG-related interventions documented among all eligible encounters; c) percentage of patient encounters in which patient intent to act is documented among all eligible encounters; and d) number of CPG resource site accesses; (4) Explore differences in the effect of MODS-APN as compared to CL-APN by APN specialty and by patient race or ethnicity; and (5) Evaluate student use and perceptions of ease of use and usability of MODS-APN. MODS-APN builds upon seminal work in the development of structured patient encounter forms that include reminders regarding protocols or guidelines. The approach is also congruent with more recent efforts to create standard clinical document architecture and related clinical templates within the Health Level 7 standards organization. Such tools have the potential to increase CPG adherence, enhance evidence-based practice, promote patient safety, and in the long term improve patient outcomes.